fix(booth): lazy-load gallery media — preload=none on video/audio

A booth of a dozen webms fetched them all at page load
(preload=metadata still pulls real byte ranges per file); nothing
loads now until the viewer hits play.

booth/templates/booth.html

@@ -29,9 +29,12 @@
       {% if it.kind == 'image' %}
         <a href="view?f={{ it.url }}"><img loading="lazy" src="{{ it.url }}" alt="{{ it.name }}"></a>
       {% elif it.kind == 'video' %}
-        <video controls preload="metadata" src="{{ it.url }}"></video>
+        {# preload="none": a booth of a dozen webms was fetching them
+           all at page load ("metadata" still pulls real ranges per
+           file); nothing loads until the viewer hits play #}
+        <video controls preload="none" src="{{ it.url }}"></video>
       {% elif it.kind == 'audio' %}
-        <audio controls preload="metadata" src="{{ it.url }}"></audio>
+        <audio controls preload="none" src="{{ it.url }}"></audio>
       {% elif it.doc %}
         <a class="dl doc" href="view?f={{ it.url }}" title="view {{ it.name }}">📄 {{ it.name }}</a>
       {% else %}